Once upon a glass. Cycles, recycles and reuses of a never-ending material

Glass can be considered a locus of meaning, a material which has been the repository of traditional knowledge and technological expertise for at least three millennia. The history of glass speaks of know-how, technological transitions, and contaminations of recipes for its manufacture, which have changed across the world over the centuries. As the amount of recovered glass from archaeological contexts is much lower compared to ceramic and metal finds, research has often considered glass as a rare material. Furthermore, glass production, in ancient times as in the present day, requires the use of selected raw materials and noticeable amounts of fuel, making reuse and recycling practices necessary to foster sustainability, from both an economical and an environmental perspective. Latin authors, such as Juvenal and Martial, reported buyers of broken glass in Imperial Rome, presumably destined for recycling. Archaeometry has also provided data that allow, today, to clarify different aspects related to production cycles, uses and reuses of a material that, starting from the Roman age, became as common as modern plastics. From beakers and goblets reused with different purposes to mosaic tesserae detached for making new mosaics or to be refused and employed as “pigments” for colouring glass, this paper aims to provide an overview of reuse and recycling practices of ancient glass through a discussion of selected case studies from Roman to Middle Ages, showing how the cycle of this material can be framed as an actual example of sustainable circular economy in the past.